Method and Apparatus for Controlling Regeneration of a Particulate Filter

ABSTRACT

A method of operating an emission abatement assembly includes igniting a fuel-fired burner of the emission abatement assembly to combust soot trapped in a particulate filter of the emission abatement assembly. The method also includes detecting an engine exhaust intake failure of the emission abatement assembly. Furthermore, the method includes extinguishing the fuel-fired burner in response to detecting the engine exhaust intake failure of the emission abatement assembly. An emission abatement system is also disclosed.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to diesel emission abatementdevices.

BACKGROUND

Untreated internal combustion engine emissions (e.g., diesel emissions)include various effluents such as oxides of nitrogen (NOx),hydrocarbons, and carbon monoxide, for example. Moreover, the untreatedemissions from certain types of internal combustion engines, such asdiesel engines, also include particulate carbon-based matter or “soot”.Federal regulations relating to soot emission standards are becomingmore and more rigid thereby furthering the need for devices and/ormethods which remove soot from engine emissions.

The amount of soot released by an engine system may be reduced by theuse of an emission abatement device such as a filter or trap. Such afilter or trap is periodically regenerated in order to remove the soottherefrom. The filter or trap may be regenerated by use of a burner toburn the soot trapped in the filter.

SUMMARY

According to one aspect of the disclosure, a method of operating anemission abatement assembly includes detecting a regeneration event fora particulate filter of the emission abatement assembly. The methodfurther includes detecting whether an engine exhaust intake failure ofthe emission abatement assembly exists. The method may also includeigniting the fuel-fired burner of the emission abatement assembly toregenerate the particulate filter in response to detecting theregeneration event and detecting that the engine exhaust intake failuredoes not exist.

According to another aspect of the disclosure, a method of operating anemission abatement assembly includes igniting a fuel-fired burner of theemission abatement assembly to combust soot trapped in a particulatefilter of the emission abatement assembly. The method also includesdetecting an engine exhaust intake failure of the emission abatementassembly. Furthermore, the method includes extinguishing the fuel-firedburner in response to detecting the engine exhaust intake failure of theemission abatement assembly.

According to yet another aspect of the disclosure, an emission abatementsystem includes a particulate filter, a fuel-fired burner, a sensor anda controller. The particulate filter traps particulates of engineexhaust as engine exhaust flows between an inlet to an outlet of theparticulate filter. The fuel-fired burner includes an engine exhaustinlet via which engine exhaust is introduced to the fuel-fired burner,an air inlet via which a flow of air is introduced into the fuel-firedburner, and a fuel inlet nozzle via which a flow of fuel is introducedin the fuel-fired burner. The fuel-fired burner is coupled to theparticulate filter inlet to supply the particulate filter with engineexhaust and in response to being ignited to supply the particulatefilter with heat to combust soot trapped in the particulate filter. Thesensor comprises a inlet-side port proximate to the particulate filterinlet and an outlet-side port proximate to the particulate filteroutlet. The sensor generates a signal indicative a differential pressuresensed between the inlet-side port and the outlet-side port. Thecontroller detects whether an engine exhaust inlet failure exists basedupon the signal from the sensor, and controls burning of the fuel-firedburner based upon detection of an engine exhaust inlet failure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear elevational view of an on-highway truck with anemission abatement assembly installed thereon;

FIG. 2 is a perspective view of an emission abatement assembly;

FIG. 3 is an elevational view of the end of the emission abatementassembly as viewed in the direction of the arrows of line 3-3 of FIG. 2;

FIG. 4 is a cross sectional view of the emission abatement assembly ofFIG. 2 taken along the line 4-4 of FIG. 3, as viewed in the direction ofthe arrows, note that the filter housing and the collector housing arenot shown in cross section for clarity of description;

FIG. 5 is an enlarged cross sectional view of the fuel-fired burner ofthe emission abatement assembly of FIG. 4;

FIG. 6 is an enlarged cross sectional view of the mixing baffle of thefuel-fired burner of FIGS. 2-5;

FIG. 7 is a diagrammatic internal top view of a fuel-fired burner;

FIG. 8 is a diagrammatic internal top view of an alternative fuel-firedburner;

FIG. 9 is a block diagram of an illustrative emission abatementassembly;

FIG. 10 is a block diagram of an illustrative sensor of the emissionabatement assembly; and

FIG. 11 is a flowchart of a control routine for operating a fuel-firedburner in an emission abatement assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

As will herein be described in more detail, FIG. 1 illustratively showsemission abatement assemblies 10, 12 for use with an internal combustionengine, such as the diesel engine of an on-highway truck 14. Asillustratively shown in FIG. 1, each of the emission abatementassemblies 10, 12 has a fuel-fired burner 16, 18 and a particulatefilter 20, 22, respectively. The fuel-fired burners 16, 18 arepositioned upstream (relative to exhaust gas flow from the engine) fromthe respective particulate filters 20, 22. During operation of theengine, exhaust gas flows through a split exhaust gas inlet pipe 19before entering the emission abatement assemblies 10, 12, and thus theparticulate filters 20, 22 thereby trapping soot in the filters. Treatedexhaust gas is released into the atmosphere through exhaust pipes 24,26. From time to time during operation of the engine, the fuel-firedburner 16 regenerates the particulate filter 20 and the fuel-firedburner 18 regenerates the particulate filter 22. Also shown in FIG. 1are fuel lines 37, 41 and air lines 39, 43 for the emission abatementassemblies 10, 12, respectively.

Referring now to FIGS. 2-6, the emission abatement assembly 10 is shownin greater detail. It should be appreciated that the emission abatementassembly 10 is substantially identical to the emission abatementassembly 12. As such, the discussion relating to the emission abatementassembly 10 of FIGS. 2-6 is relevant to the emission abatement assembly12.

As shown in FIGS. 4 and 5, the fuel-fired burner 16 includes a housing15 having a combustion chamber 17 positioned therein. The exhaust gasinlet pipe 19 is illustratively shown in FIGS. 4 and 5 as being disposedthrough an inlet 21 of the burner housing 15 allowing the pipe 19 toconduct exhaust gas from a diesel engine (not shown) into the burnerhousing 15. The pipe 19 includes an elbow 23 disposed on an outlet endof the pipe 19 which is received by the inlet 21 and positioned in thehousing 15. The elbow 23 allows exhaust gas flowing through the pipe 19to be directed toward a wall 25 of the housing 15 to impinge upon thewall 25 prior to reaching the combustion chamber 17. FIG. 7 shows adiagrammatic internal top view (with respect to the orientation shown inFIG. 1) of the fuel-fired burner 16, which illustrates a manner in whichthe exhaust gas flows into the housing 15 and impinges upon the wall 25.As indicated by the arrows, the exhaust gas, upon impinging the wall 25,flows in a swirling pattern as the exhaust gas also flows downstream(relative to exhaust gas flow) through the housing 15 towards the filter20.

Again referring to FIGS. 4 and 5, the combustion chamber 17 includes awall 45 circumscribing a space 47 where the flame of the burner 16 ispositioned. The wall 45 is open at its end proximate to the filter 20with the wall 45 including a number of gas inlet openings 22 definedtherein. The exhaust gas is permitted to flow into the combustionchamber 17 through the inlet openings 22. In such a way, a flame presentinside the combustion chamber 17 is protected from the full engineexhaust gas flow, while controlled amounts of engine exhaust gas arepermitted to enter the combustion chamber 17 to provide oxygen tofacilitate combustion of the fuel supplied to the burner 12. Directingthe exhaust gas through the elbow 23 such that it is not exiting thepipe 19 directly toward the combustion chamber 17 further protects theflame. As the exhaust gas impinges upon the wall 25 and swirls throughthe housing 15, the exhaust gas will diffuse such that a portion of itenters the combustion chamber 17. The exhaust gas not entering thecombustion chamber 17 is directed through a number of openings 35defined in a shroud 27.

The fuel-fired burner 16 also includes an electrode assembly having apair of electrodes 28, 30 as illustratively shown in FIGS. 3-5. Whenpower is applied to the electrodes 28, 30, a spark is generated in thegap 32 between the electrodes 28, 30. Fuel flows from the fuel line 37and enters the fuel-fired burner 16 through a fuel inlet nozzle 34 andis advanced through the gap 32 between the electrodes 28, 30 therebycausing the fuel to be ignited by the spark generated by the electrodes28, 30. It should be appreciated that the fuel entering the nozzle 34 isgenerally in the form of a controlled air/fuel mixture.

The fuel-fired burner 16 also includes a combustion air inlet 36. An airpump, or other pressurized air source such as the truck's turbochargeror air brake system, generates a flow of pressurized air which isadvanced to the combustion air inlet 36. During regeneration of theparticulate filter 20, a flow of air is introduced into the fuel-firedburner 16 through the air line 39 and the combustion air inlet 36 toprovide oxygen (in addition to oxygen present in the exhaust gas) tosustain combustion of the fuel.

As shown in FIG. 4, the particulate filter 20 is positioned downstreamfrom the outlet 40 of the housing 15 of the fuel-fired burner 16. Theparticulate filter 20 includes a filter substrate 42. As shown in FIG.4, the substrate 42 is positioned in a filter housing 44. An inlet 49 ofthe filter housing 44 is secured to an outlet 40 of the burner housing15. As such, gas exiting the burner housing 15 is directed into thefilter housing 44 and through the substrate 42. The particulate filter20 may be any type of commercially available particulate filter. Forexample, the particulate filter 20 may be embodied as any known exhaustparticulate filter such as a “deep bed” or “wall flow” filter. Deep bedfilters may be embodied as metallic mesh filters, metallic or ceramicfoam filters, ceramic fiber mesh filters, and the like. Wall flowfilters, on the other hand, may be embodied as a cordierite or siliconcarbide ceramic filter with alternating channels plugged at the frontand rear of the filter thereby forcing the gas advancing therethroughinto one channel, through the walls, and out another channel. Moreover,the filter substrate 42 may be impregnated with a catalytic materialsuch as, for example, a precious metal catalytic material. The catalyticmaterial may be, for example, embodied as platinum, rhodium, palladium,including combinations thereof, along with any other similar catalyticmaterials. Use of a catalytic material lowers the temperature needed toignite trapped soot particles.

The filter housing 44 is secured to a housing 46 of a collector 48.Specifically, an outlet 50 of the filter housing 44 is secured to aninlet 52 of the collector housing 46. As such, processed (i.e.,filtered) exhaust gas exiting the filter substrate 42 (and hence thefilter housing 44) is advanced into the collector 48. The processedexhaust gas is then advanced through a gas outlet 54. In FIG. 1, the gasoutlet 54 is coupled to the exhaust pipe 24, which conducts theprocessed exhaust gas into the atmosphere. However, it should beappreciated that the gas outlet 54 may be coupled to a subsequentemission abatement device (e.g., see FIG. 9) allowing further exhaustgas processing prior to the exhaust gas being released into theatmosphere if the engine's exhaust system is equipped with such adevice.

Referring again to FIGS. 4-6, a mixing baffle 56 is positioned in theburner housing 15. The mixing baffle 56 is positioned between the shroud27 and the outlet 40 of the burner housing 15. In the illustrativeembodiment described herein, the mixing baffle 56 includes a domeddiverter plate 58, a perforated annular ring 60, and a collector plate62. As shown in FIGS. 4 and 5, the collector plate 62 is welded orotherwise secured to the inner surface of the burner housing 15. Thecollector plate 62 has a hole 64 in the center thereof. The perforatedannular ring 60 is welded or otherwise secured to the collector plate62. The inner diameter of the annular ring 60 is larger than thediameter of the hole 64. As such, the annular ring 60 surrounds the hole64 of the collector plate 62. The diverter plate 58 is welded orotherwise secured to the end of the annular ring 60 opposite to the endthat is secured to the collector plate 62. The diverter plate 58 issolid (i.e., it does not have holes or openings formed therein), and, assuch, functions to block the flow of exhaust gas linearly through themixing baffle 56. Instead, the diverter plate 58 diverts the flow ofexhaust gas radially outwardly.

The mixing baffle 56 functions to mix the hot flow of exhaust gasdirected through the combustion chamber 17 and cold flow of exhaust gasthat bypasses the combustion chamber 17 during filter regenerationthereby introducing a mixed flow of exhaust gas into the particulatefilter 20. In particular, as described above, the flow of exhaust gasswirling in the combustion chamber housing 15 (see FIG. 7) is split intotwo flows—(i) a cold bypass flow which bypasses the combustion chamber17 and is advanced through the openings 35 of the shroud 27 and, (ii) ahot combustion flow which flows into the combustion chamber 17 where itis significantly heated by the flame present therein. The mixing baffle56 forces both flows together through a narrow area and then causes sucha concentrated flow to then flow radially outwardly thereby mixing thetwo flows together. To do so, the cold flow of exhaust gas advancesthrough the openings 35 in the shroud 27 and thereafter is directed intocontact with the upstream face 66 of the collector plate 62. The shapeof the collector plate 62 directs the cold flow toward its hole 64.

Likewise, the hot flow of exhaust gas is directed toward the hole of thecollector plate 62. In particular, the hot flow of exhaust gas isprevented from axially exiting the combustion chamber 17 by a domedflame catch 68. The flame catch 68 forces the hot flow of exhaust gasradially outwardly through a number of openings 70 defined in aperforated annular ring 72, which is similar to the perforated annularring 62 of the mixing baffle 56. The hot flow of exhaust gas is thendirected toward the upstream face 66 of the collector plate 62 by acombination of surfaces including the downstream face 74 of the shroud27 and the wall 25 of the burner housing 15. The hot flow of exhaust gasthen contacts the upstream face 66 of the collector plate where theshape of the plate 62 causes the hot flow of exhaust gas to be directedtoward the hole 64. This begins the mixing of the hot flow of exhaustgas with the cold flow of exhaust gas.

Mixing is continued as the cold and hot flows of exhaust gas enter thehole 64 of the collector plate 62. The partially mixed flow of gases isdirected into contact with the diverter plate 58. The diverter plate 58blocks the linear flow of gases and directs them outwardly in radialdirections away from the diverter plate 58. The flow of exhaust gas isthen directed through a number of openings 76 formed in the perforatedannular ring 62 of the mixing baffle 56. This radial outward flow ofexhaust gas impinges on the inner surface of the burner housing 15 andis directed through the outlet 40 of the burner housing 15 and into theinlet of the filter housing 44 where the mixed flow of exhaust gas isutilized to regenerate the filter substrate 42.

Hence, the elbow 23 causes the exhaust gas entering the housing 15 toflow in a swirling manner while the exhaust gas flows downstream throughthe housing 15 as the exhaust gas is split into the bypass andcombustion flow. The mixing baffle 56 forces the mixing of thenon-homogeneous exhaust gas flow through a narrow area, and then causesthe mixed flow to expand outwardly. Swirling the exhaust gas enteringthe housing 15 and forcing it through the mixing baffle 56, prevents theformation of a center flow or center jet of hot gas from being impingedon the filter substrate 42. This provides a more homogeneous mixture ofthe hot and cold flows created prior to introduction of the combinedflow onto the face of the filter substrate thereby increasing filterregeneration efficiency and reducing the potential for filter damage dueto hot spots. It should be appreciated that the elbow 23 and the mixingbaffle 56 may be implemented separately, or together, as describedherein.

FIG. 8 shows a diagrammatic internal top view of the emission abatementassembly 10 implementing an alternative housing 15 and exhaust gas inletpipe configuration 19. In this illustrative configuration, the elbow 23is eliminated and the pipe 19 is extended through an opening formed inthe housing 15 such that the exhaust gas flowing through the pipe 19 isdirected along the wall 25 upon entering the housing 15. This allows theexhaust flow to impinge upon the wall 25 along its flow path, whichinduces the flow of exhaust gas into a swirling pattern similar to thatinduced with the configuration shown in FIG. 7. Similar to theconfiguration shown in FIG. 7, the configuration of FIG. 8 may beimplemented with the mixing baffle 56.

Referring now to FIG. 9, there is illustratively shown a diagrammaticview of an emission abatement system 90 to abate emissions generated byan internal combustion engine 92. The emission abatement system 90includes an emissions abatement assembly 10 having a fuel-fired burner16 disposed downstream of the engine 92 along the exhaust path 94, theengine 92 being a diesel engine in this illustrative embodiment. Theemission abatement assembly 10 further includes a particulate filter 20positioned downstream of the fuel-fired burner 16 along the exhaust path94.

Also shown in FIG. 9 is an electronic control unit (ECU) or “electroniccontroller” 104. The electronic controller 104 is typically positionedin a housing and located internally of the truck 14 as previouslydiscussed in regard to FIG. 1. The electronic controller 104 is, inessence, the master computer responsible for interpreting electricalsignals sent by sensors associated with the emission abatement assembly10 (and in some cases, the engine 92) and for activatingelectronically-controlled components associated with the emissionabatement assembly 10. For example, the electronic controller 104 isoperable to, amongst many other things, determine when the particulatefilter 20 of the emission abatement assembly 10 is in need ofregeneration, calculate and control the amount and ratio of air and fuelto be introduced into the fuel-fired burner 16, determine thetemperature in various locations within the emission abatement assembly10, operate numerous air and fuel valves, and communicate with an enginecontrol unit (not shown) associated with the engine 92 of the truck 14.It should be appreciated that the electronic controller 104 may alsodetermine which emission abatement assembly 10, 12 needs to beregenerated in a dual arrangement similar to that described in regard toFIG. 1.

To carry out these tasks, the electronic controller 104 includes anumber of electronic components commonly associated with electronicunits utilized in the control of electromechanical systems. For example,the electronic controller 104 may include, amongst other componentscustomarily included in such devices, a processor such as amicroprocessor 106 and a memory device 108 such as a programmableread-only memory device (“PROM”) including erasable PROM's (EPROM's orEEPROM's). The memory device 108 is provided to store, amongst otherthings, instructions in the form of, for example, a software routine (orroutines) which, when executed by the processor 106, allows theelectronic controller 104 to control operation of the emission abatementsystem 90.

The electronic controller 104 also includes an analog interface circuit110. The analog interface circuit 110 converts the output signals fromthe various sensors (e.g., pressure sensors, temperature sensors) into asignal, which is suitable for presentation to an input of themicroprocessor 106. In particular, the analog interface circuit 110, byuse of an analog-to-digital (A/D) converter (not shown) or the like,converts the analog signals generated by the sensors into a digitalsignal for use by the processor 106. It should be appreciated that theA/D converter may be embodied as a discrete device or number of devices,or may be integrated into the microprocessor 106. It should also beappreciated that if any one or more of the sensors associated with theemission abatement assembly 10 generate a digital output signal, theanalog interface circuit 110 may be bypassed.

Similarly, the analog interface circuit 110 converts signals from themicroprocessor 106 into an output signal which is suitable forpresentation to the electrically-controlled components associated withthe emission abatement assembly 10 (e.g., the fuel injectors, airvalves, igniters, pump motor, etcetera). In particular, the analoginterface circuit 110, by use of a digital-to-analog (D/A) converter(not shown) or the like, converts the digital signals generated by theprocessor 106 into analog signals for use by theelectronically-controlled components associated with the emissionabatement system 90. It should be appreciated that, similar to the A/Dconverter described above, the D/A converter may be embodied as adiscrete device or number of devices, or may be integrated into theprocessor 106. It should also be appreciated that if any one or more ofthe electronically-controlled components associated with the emissionabatement assembly 10 operate on a digital input signal, the analoginterface circuit may be bypassed.

Hence, the electronic controller 104 may be operated to controloperation of the fuel-fired burner 16. In particular, the electroniccontroller 104 executes a routine including, amongst other things, aclosed-loop control scheme in which the electronic controller 104monitors outputs of the sensors associated with the emission abatementassembly 10 to control the inputs to the electronically-controlledcomponents associated therewith. To do so, the electronic controller 104communicates with the sensors associated with the emission abatementassembly 10 to determine, amongst numerous other things, the temperatureat various locations within the emission abatement assembly 10 and thepressure drop across the filter substrate 42 of the filter 20. Armedwith this data, the electronic controller 104 performs numerouscalculations each second, including looking up values in preprogrammedtables, in order to execute algorithms to perform such functions asdetermining when or how long the fuel injectors are operated,controlling the power level input to the electrodes 28, 30 of the burner16, controlling the air advanced through a combustion air inlet 36,detecting engine exhaust intake failures, etcetera.

It should be appreciated that the electronic controller 104 maycommunicate directly with the various sensors associated with theemission abatement assembly 10, or may obtain the output from thesensors from an engine control unit (not shown) associated with theengine 92 via a controller area network (CAN) interface (not shown),known to those of skill in the art. Alternatively, exhaust mass flow maybe calculated by the electronic controller 104 in a conventional mannerby use of engine operation parameters such as engine RPM, turbo boostpressure, and intake manifold temperature (along with other knownparameters such as engine displacement). It should be appreciated thatthe electronic controller 104 may itself calculate the mass flow, or mayobtain the calculated mass flow from the engine control unit of theengine 92 via the CAN interface.

As previously discussed, during operation of the engine 92, the filter20 eventually becomes full of soot from filtering the exhaust gasgenerated by the engine 92 and needs to be regenerated in order toreduce engine 92 exhaust back pressure for proper engine 92 operation.The processor 106 may be programmed to control the burner 16 based uponvarious regeneration events such as, for example, predetermined timeintervals, event sensing, or other triggering occurrences known to thosein the art. Once the fuel-fired burner 16 is activated, it begins toproduce heat. Such heat is directed downstream (relative to exhaust gasflow) and into contact with the upstream face of the particulate filter20. The heat ignites and burns soot particles trapped in the filtersubstrate 42 thereby regenerating the particulate filter 20.Illustratively, heat in the range of 600-650 degrees Celsius may besufficient to regenerate a non-catalyzed filter, whereas heat in therange of 300-350 degrees Celsius may be sufficient to regenerate acatalyzed filter.

In an illustrative embodiment, regeneration of the particulate filter 20may take only a few minutes. The controller 104 may ignite and burn thefuel-fired burner 16 for the duration of the regeneration. For example,the controller 104 may burn the fuel-fired burner 16 for a period oftime that has been found sufficient to regenerate the particulate filter20. In other embodiments, the controller 104 may burn the fuel-firedburner 16 until the controller 104 detects regeneration has completed.For example, the controller 104 may extinguish the burner 16 in responseto sensed temperatures indicating completion of the regeneration. Thecontroller 104 may also extinguish the burner 16 in response to adifferential pressure across the particulate filter 20 having apredetermined relationship to (e.g. less than) a differential pressureassociated with a regenerated filter.

Moreover, it should be appreciated that regeneration of the particulatefilter 20 may be self-sustaining once initiated by heat from the burner16, respectively. Specifically, once the filter 20 is heated to atemperature at which the soot particles trapped therein begin to ignite,the ignition of an initial portion of soot particles trapped therein maycause the ignition of the remaining soot particles much in the same waya cigar slowly burns from one end to the other. In essence, as the sootparticles “burn,” an amount of heat is released in the “burn zone.”Locally, the soot layer (in the burn zone) is now much hotter than theimmediate surroundings. As such, heat is transferred to the as yetun-ignited soot layer downstream of the burn zone. The energytransferred may be sufficient to initiate oxidation reactions that raisethe un-ignited soot to a temperature above its ignition temperature. Asa result of this, heat from the fuel-fired burner 16 may only berequired to commence the regeneration process of the filter 20 (i.e.,begin the ignition process of the soot particles trapped therein).

During its operation, the burner 16 receives an air/fuel mixture, whichmay be controlled through control of a fuel pump 93 and the addition ofcombustion air through combustion air inlet 36 of the burner 16. Asillustratively shown in FIG. 9, the burner 16 receives fuel from thefuel supply 117 through the fuel line 119. During operation of theburner 16, the amount of usable oxygen present in the exhaust gas maynot be sufficient to allow the burner 16 to generate enough heat toregenerate the particulate filter 20. Supplemental oxygen, therefore,may be supplied from the air supply 112 to the burner 16 via an air line113 and valve 114. The air supply 112 may be implemented through variousforms, such as an air pump, a turbocharger or supercharger of the engine92, or the truck's air brake system.

In one embodiment, the controller 104 attempts to detect engine exhaustintake failures and attempts to respond to such failures. An engineexhaust intake failure may result from the engine exhaust inlet pipe 19becoming disconnected from an emission abatement assembly 10, 12. As aresult, not only will the emission abatement assembly 10, 12 not receiveengine exhaust due to the disconnected pipe but a potentially dangeroussituation may occur if the burner 16 is ignited and/or permitted tocontinue to burn while the pipe 19 is disconnected. In particular,igniting and/or operating the burner 16 with the pipe 19 disconnectedmay result in fuel and/or flame exiting the inlet 21 of the burner 16.Such fuel and/or flame exiting the inlet 21 may ignite materialsexternal to the emission abatement assembly 10, 12. Similarly, an engineexhaust inlet failure may occur as a result of a hole forming in theinlet pipe 19 and/or burner housing 15 due to a puncture, corrosion, orsome other cause. In such a situation, again igniting and/or operatingthe burner 16 may result in fuel and/or flame exiting the hole formed inthe inlet pipe 19 and/or burner housing 15. As noted above, such fueland/or flame exiting the emission abatement assembly 10, 12 may ignitematerial external to the emission abatement assembly 10, 12.

To detect such engine exhaust intake failures, the controller 104 in oneembodiment receives a signal S from a sensor 120. The sensor 120 has aninlet-side port 121 in fluidic communication with an interior positionof the emission abatement assembly 10 that is proximate the inlet 49 ofthe filter housing 44. As such, the sensor 120 may sense an inlet-sidepressure of the particulate filter 20 via the inlet-side port 121.Similarly, the sensor 120 has an outlet-side port 125 in fluidiccommunication with an interior position of the emission abatementassembly 10 that is proximate the outlet 50 of the filter housing 44. Assuch, the sensor 120 may sense an outlet-side pressure of theparticulate filter 20 via the outlet-side port 125.

In one embodiment, the sensor 120 comprises a differential pressuresensor 127 coupled between the inlet-side port 121 and the outlet-sideport 125. In such an embodiment, the sensor 120 may generate the signalsuch that the signal is indicative of a differential pressure sensed bythe differential pressure sensor 127. As depicted in FIG. 10, the sensor120 may alternatively include an inlet-side pressure sensor 129 coupledto the inlet-side port 121 and an outlet-side pressure sensor 131coupled to the outlet-side port 125. The inlet-side pressure sensor 129may sense an inlet-side pressure of the particulate filter 20 and theoutlet-side pressure sensor 129 may sense an outlet-side pressure of theparticulate filter 20. In a such an embodiment, the sensor 120 maygenerate the signal such that the signal includes both an inlet-sidepressure signal indicative of the sensed inlet-side pressure and anoutlet-side pressure signal indicative of the sensed outlet-sidepressure. In another embodiment, the sensor 120 may process the sensedpressures to generate a signal indicative of the differential pressurebetween the inlet-side and outlet-side of the particulate filter 20. Insuch an embodiment, the sensor 120 may include a differential amplifierthat receives a signal from the inlet-side pressure sensor 129indicative of the inlet-side pressure and a signal from the outlet-sidepressure sensor 131 indicative of the outlet-side pressure and generatesa signal indicative of a differential pressure between the inlet-sidepressure and the outlet-side pressure of the particulate filter 20.

FIG. 11 shows an illustrative control routine 200 which the controller104 may execute to control regeneration of the particulate filter 20. Inparticular, the controller 104 in response to executing the controlroutine 200 attempts to detect engine exhaust intake failures andattempts to respond to such failures. As mentioned above, an engineexhaust intake failure may result from the engine exhaust inlet pipe 19becoming disconnected from an emission abatement assembly 10, 12. As aresult, not only will the emission abatement assembly 10, 12 not receiveengine exhaust due to the disconnected pipe but a potentially dangeroussituation may occur if the burner 16 is ignited or kept burning whilethe pipe 19 is disconnected.

In light of the potential dangers associated with an engine exhaustintake failure, the controller 104 as a result of executing the controlroutine 200 does not ignite the burner 16 and/or extinguishes the burner16 when such failures are detected. In one embodiment, the controller104 at 210 may determine whether a regeneration event has occurred. Inparticular, the controller 104 may determine that an event has occurredthat indicates that the particulate filter 20 is in need of beingregenerated. For example, the controller 104 may determine that aregeneration event has occurred in response to the pressure across thefilter 20 having a predetermined relationship to (e.g. less than) apredetermined differential pressure threshold. The controller 104 mayalso determine that a regeneration event has occurred in response todetermining that a predetermined time period since a previousregeneration has expired. The controller 104 may also determine that aregeneration event has occurred in response to determining that anestimated amount of soot trapped by the particulate filter 20 has apredetermined relationship to (e.g. exceeds) a threshold soot level.

If the controller 104 determines that a regeneration event has notoccurred, then the controller 104 may return to 210 in order toperiodically check whether a regeneration event has occurred. Inresponse to detecting a regeneration event, the controller 104 mayproceed to 220 to determine whether an engine exhaust intake failure hasoccurred. The controller 104 may determine whether an engine exhaustintake failure has occurred based upon pressures exerted on and/oracross the particulate filter 20. In particular, the controller 104 mayreceived the signal S from the sensor 120 and determine whether anengine exhaust intake failure has occurred. As mentioned above, thesignal S may comprise a signal indicative of the differential pressureacross the particulate filter 20 or may comprise signals indicative ofthe pressures on the inlet-side and the outlet-side of the particulatefilter 20. Regardless, the controller 104 based upon the signal S maymonitor the differential pressure across the particulate filter 20.

In such an embodiment, the controller 104 may determine that an engineexhaust intake failure has occurred in response to a rate of change inthe differential pressure across the particulate filter 20 having apredetermined relationship to (e.g. greater than) a threshold rate ofchange. During normal operation of the emission abatement system 90, therate of change of the differential pressure gradually increases as theparticulate filter 20 traps soot and gradually decreases as soot isburnt off by the burner 16. In contrast, an engine exhaust intakefailure for the emission abatement assembly 10 may result in a sharpdecrease in the differential pressure. For example, upon the gas inletpipe 19 becoming disconnected from the emission abatement assembly 10,the pressure on the inlet-side of the particulate filter 20 may sharplydrop to near atmospheric pressure. Likewise, the differential pressureacross the particulate filter 20 may quickly drop to near zero. Thus, bysetting the threshold differential pressure to a level less thantypically experienced during normal operation, the controller 104 maydetect an engine exhaust intake failure in response to the differentialpressure across the particulate filter 20 having a predeterminedrelationship to (e.g. greater than) the threshold differential pressure.

In another embodiment, the controller 104 may likewise monitor thedifferential pressure across the particulate filter 20 based upon thereceived signal S. However, instead of detecting an emission abatementfailure based upon a rate of change in the differential pressure, thecontroller 104 may detect an engine exhaust intake failure in responseto the differential pressure across the particulate filter 20 having apredetermined relationship to (e.g. less than) a threshold differentialpressure. As mentioned above, the differential pressure across theparticulate filter 20 may drop to near zero in response to an engineexhaust intake failure. Accordingly, in one embodiment, a thresholddifferential pressure may be defined that specifies differentialpressures below which are indicative of an engine exhaust intakefailure. Thus, the controller 104 may detect an engine exhaust intakefailure in response to the differential pressure across the particulatefilter 20 having a predetermined relationship to (e.g. less than) athreshold differential pressure associated with an engine exhaust intakefailure.

In other embodiments, the controller 104 may detect an engine exhaustintake failure based upon solely an inlet-side pressure of theparticulate filter 20 instead of the differential pressure across theparticulate filter 20. Again, the rate of change of the inlet-sidepressure is likely to sharply decrease in response to an engine exhaustintake failure. Moreover, the inlet-side pressure is likely to drop tonear atmospheric levels in response to an engine exhaust intake failure.Accordingly, a threshold pressure may be defined that specifiespressures below which are indicative of an engine exhaust intakefailure. The controller may then detect an engine exhaust intake failurein response the inlet-side pressure of the particulate filter 20 havinga predetermined relationship to (e.g. less than) the threshold pressureassociated with an engine exhaust intake failure. Similarly, a thresholdrate of change may be defined that specifies rates above which areindicative of an engine exhaust intake failure. The controller 104 maythen detect an engine exhaust intake failure in response to a rate ofchange of the inlet-side pressure of the particulate filter 20 having apredetermined relationship to (e.g. greater than) the threshold rate ofchange associated with an engine exhaust intake failure.

If the controller 104 determines that the an engine exhaust intakefailure has not occurred, then the controller 104 may proceed to 260 toextinguish the fuel-fired burner 16 or ensure the fuel-fired burner isextinguished. Otherwise, the controller 104 at 230 may ignite thefuel-fired burner 16. To this end, the controller 104 may active thefuel pump 93 to deliver fuel and may open the valve 114 to deliver airto the burner 16.

After igniting the fuel-fired burner 16, the controller 104 at 240 mayagain determine whether an engine exhaust intake failure has occurred.The controller 104 may make such a determination in a manner similar tothe manner discussed above in regard to 220. Like 220, if the controller104 determines an engine exhaust intake failure has occurred, thecontroller 104 may proceed to 260 to extinguish the fuel-fired burner16.

At 250, the controller 104 may determine whether the regeneration of theparticulate filter 20 is complete. If complete, the controller 104 mayproceed to 260 to extinguish the fuel-fired burner 16. If not complete,the controller 104 may return to 240 to ensure an engine exhaust intakefailure has not occurred. At 250, the controller 104 may use varioustechniques to detect completion of the filter regeneration. For example,the controller 104 may determine the regeneration is complete inresponse to determining that a specified period of time sufficient toregenerate the particulate filter 20 has elapsed since igniting thefuel-fired burner 16. The controller 104 may also determine theregeneration is complete based upon sensed temperatures of the emissionsabatement assembly 20. Further, the controller 104 may determine theregeneration is complete based upon the differential pressure across theparticulate filter 20. As mentioned above, the differential pressureacross the particulate filter 20 gradually decreases as the particulatefilter 20 is regenerated. Accordingly, a threshold differential pressuremay be defined that specifies a differential pressure that is indicativeof a regenerated filter. The controller 104 may then determine thatregeneration of the particulate filter 20 is complete in response todetermining that the differential pressure across the particulate filter20 has a predetermined relationship to (e.g. less than) a thresholddifferential pressure associate with a regenerated filter.

As noted above, the controller 104 may also detect an engine exhaustintake failure in response to the differential pressure across theparticulate filter 20 having a predetermined relationship to (e.g. lessthan) a threshold differential pressure associated with an engineexhaust intake failure. In practice, the threshold differential pressureassociated with an engine exhaust intake failure is less than thethreshold differential pressure associated with a regenerated filter.Accordingly, in one embodiment, the threshold differential pressures fora regenerated filter and an engine exhaust intake failure are definedsuch that the controller 104 may distinguish between a regeneratedfilter and an engine exhaust intake failure.

At block 260, the controller 104 may extinguish the fuel-fired burner16. In one embodiment, the controller 104 closes the valve 114 to ceasedelivery of air from the air supply 112 and deactivate the fuel pump 93to cease delivery of fuel from the fuel supply 117. However, it shouldbe appreciated that the fuel-fired burner 16 may also be extinguished bymerely deactivating the fuel pump 92.

While the disclosure is susceptible to various modifications andalternative forms, specific exemplary embodiments thereof have beenshown by way of example in the drawings and has herein be described indetail. It should be understood, however, that there is no intent tolimit the disclosure to the particular forms disclosed, but on thecontrary, the intention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the disclosure.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the apparatus, systems, and methodsdescribed herein. It will be noted that alternative embodiments of theapparatus, systems, and methods of the present disclosure may notinclude all of the features described yet still benefit from at leastsome of the advantages of such features. Those of ordinary skill in theart may readily devise their own implementations of apparatus, systems,and methods that incorporate one or more of the features of the presentdisclosure and fall within the spirit and scope of the presentdisclosure. For example, it should be appreciated that the order of manyof the steps of the control routines described herein may be altered.Moreover, many steps of the control routines may be performed inparallel with one another.

1. A method of operating an emission abatement assembly, the methodcomprising: detecting a regeneration event for a particulate filter ofthe emission abatement assembly, detecting whether an engine exhaustintake failure of the emission abatement assembly exists, and ignitingthe fuel-fired burner of the emission abatement assembly to regeneratethe particulate filter in response to detecting the regeneration eventand detecting that the engine exhaust intake failure does not exist. 2.The method of claim 1, further comprising monitoring a differentialpressure across the particulate filter, wherein detecting whether theengine exhaust intake failure exists comprises detecting whether theengine exhaust intake failure exists based upon the differentialpressure across the particulate filter.
 3. The method of claim 1,further comprising monitoring a differential pressure across theparticulate filter, wherein detecting whether the engine exhaust intakefailure exists comprises detecting that the engine exhaust intakefailure exists in response to determining that the differential pressureacross the particulate filter has a predetermined relationship to athreshold differential pressure.
 4. The method of claim 1, furthercomprising monitoring a differential pressure across the particulatefilter, wherein detecting whether the engine exhaust intake failureexists comprises detecting whether the engine exhaust intake failureexists based upon a rate of change of the differential pressure acrossthe particulate filter.
 5. The method of claim 1, further comprisingmonitoring a differential pressure across the particulate filter,wherein detecting whether the engine exhaust intake failure existscomprises detecting that the engine exhaust intake failure exists inresponse to determining that a rate of change of the differentialpressure across the particulate filter has a predetermined relationshipto a threshold rate of change.
 6. The method of claim 1, furthercomprising monitoring a first pressure toward an inlet of theparticulate filter, wherein detecting whether the engine intake failureexists comprises detecting whether the engine exhaust intake failureexists based upon the first pressure toward the inlet of the particulatefilter.
 7. The method of claim 1, further comprising monitoring a firstpressure toward an inlet of the particulate filter, and monitoring asecond pressure toward an outlet of the particulate filter, whereindetecting whether the engine intake failure exists comprises detectingwhether the engine exhaust intake failure exists based upon the firstpressure and the second pressure.
 8. A method of operating an emissionabatement assembly, the method comprising: igniting a fuel-fired burnerof the emission abatement assembly to combust soot trapped in aparticulate filter of the emission abatement assembly, detecting anengine exhaust intake failure of the emission abatement assembly, andextinguishing the fuel-fired burner in response to detecting the engineexhaust intake failure of the emission abatement assembly.
 9. The methodof claim 8, further comprising monitoring a first pressure toward aninlet of the particulate filter, wherein detecting comprises detectingthe engine exhaust intake failure based upon the first pressure towardthe inlet of the particulate filter.
 10. The method of claim 8, furthercomprising monitoring a differential pressure across the particulatefilter, wherein detecting comprises detecting the engine exhaust intakefailure in response to determining that a rate of change of thedifferential pressure across the particulate filter has a predeterminedrelationship a threshold rate of change.
 11. The method of claim 8,further comprising monitoring a differential pressure across theparticulate filter, wherein detecting the engine exhaust intake failurecomprises detecting the engine exhaust intake failure in response to thedifferential pressure across the particulate filter having apredetermined relationship to a threshold pressure associated with anengine exhaust intake failure.
 12. The method of claim 11, furthercomprising extinguishing the fuel-fired burner in response to thedifferential pressure across the particulate filter having apredetermined relationship to a threshold pressure associated with aregenerated particulate filter.
 13. The method of claim 12, wherein thethreshold pressure associated with an engine exhaust intake failure isless than the threshold pressure associated with a regeneratedparticulate filter.
 14. An emission abatement system, comprising aparticulate filter to trap particulates of engine exhaust as engineexhaust flows between an inlet to an outlet of the particulate filter, afuel-fired burner comprising an engine exhaust inlet via which engineexhaust is introduced to the fuel-fired burner, an air inlet via which aflow of air is introduced into the fuel-fired burner, and a fuel inletnozzle via which a flow of fuel is introduced in the fuel-fired burner,the fuel-fired burner being coupled to the particulate filter inlet tosupply the particulate filter with engine exhaust and in response tobeing ignited to supply the particulate filter with heat to combust soottrapped in the particulate filter, a sensor comprising a inlet-side portproximate to the particulate filter inlet and an outlet-side portproximate to the particulate filter outlet, the sensor to generate asignal indicative a differential pressure sensed between the inlet-sideport and the outlet-side port, and a controller to detect whether anengine exhaust inlet failure exists based upon the signal from thesensor, and to control burning of the fuel-fired burner based upondetection of an engine exhaust inlet failure.
 15. The emission abatementsystem of claim 14, wherein the sensor comprises a differential pressuresensor, and the differential pressure sensor comprises the inlet-sideport proximate to the particulate filter inlet and the outlet-side portproximate the particulate filter outlet.
 16. The emission abatementsystem of claim 14, wherein the sensor comprises an inlet-side pressuresensor comprising the inlet-side port proximate to the particulatefilter inlet, and the sensor comprises an outlet-side pressure sensorcomprising an outlet-side port proximate the particulate filter outlet.17. The emission abatement system of claim 14 wherein the controllerdetermines that an engine exhaust inlet failure has occurred in responseto detecting based upon the signal of the sensor that a rate of changeof the differential pressure across the particulate filter has apredetermined relationship to a threshold rate of change.
 18. Theemission abatement system of claim 14 wherein the controller determinesthat an engine exhaust inlet failure has occurred in response todetecting based upon the signal of the sensor that the differentialpressure across the particulate filter has a predetermined relationshipto a threshold pressure.
 19. The emission abatement system of claim 15,further comprising a fuel supply coupled to the fuel-fired burner via afuel pump, and an air supply coupled to the fuel-fired burner via avalve, wherein the controller opens the valve and activates the fuelpump in response to determining to ignite the fuel-fired burner, andcloses the valve and deactivates the fuel pump in response todetermining to extinguish the fuel-fire burner.